Biological samples are commonly preserved to support a broad variety of biomedical and biological research that includes but is not limited to translational research, molecular medicine, and biomarker discovery. Biological samples include any samples which are of animal (including human), plant, protozoal, fungal, bacterial, viral, or other biological origin. For example, biological samples include, but are not limited to, organisms and/or biological fluids isolated from or excreted by an organism such as plasma, serum, urine, whole blood, cord blood, other blood-based derivatives, cerebral spinal fluid, mucus (from respiratory tract, cervical), ascites, saliva, amniotic fluid, seminal fluid, tears, sweat, any fluids from plants (including sap); cells (e.g., animal, plant, protozoal, fungal, or bacterial cells, including buffy coat cells; cell lysates, homogenates, or suspensions; microsomes; cellular organelles (e.g., mitochondria); nucleic acids (e.g., RNA, DNA), including chromosomal DNA, mitochondrial DNA, and plasmids (e.g., seed plasmids); small molecule compounds in suspension or solution (e.g. small molecule compounds in DMSO); and other fluid-based biological samples. Biological samples may also include plants, portions of plants (e.g., seeds) and tissues (e.g., muscle, fat, skin, etc.).
Biobanks typically store these valuable samples in containers (e.g., tubes, vials, or the like) and cryopreserve them (e.g., in freezers at −80 degrees centigrade, or lower, using liquid Nitrogen or the vapor phase above liquid Nitrogen) to preserve the biochemical composition and integrity of the frozen sample as close as possible to the in vivo state to facilitate accurate, reproducible analyses of the samples.
From time to time, it may be desirable to run one or more tests on a sample that has been frozen. For example, a researcher may want to perform tests on a set of samples having certain characteristics. A particular sample may contain enough material to support a number of different tests. In order to conserve resources, smaller samples known as aliquots are commonly taken from larger cryopreserved samples (which are sometimes referred to as parent samples) for use in one or more tests so the remainder of the parent sample will be available for one or more different future tests.
Biobanks have adopted different ways to address this need to provide sample aliquots. One option is to freeze a sample in large volume, thaw it when aliquots are requested and then refreeze any remainder of the parent sample for storage in the cryopreserved state until future aliquots are needed. This option makes efficient use of frozen storage space; yet this efficiency comes at the cost of sample quality. Exposing a sample repeatedly to freeze/thaw cycles can degrade the sample's critical biological molecules (e.g., RNA) and damage biomarkers, either of which could compromise the results of any study using data obtained from the damaged samples.
Another option is to freeze a sample in large volume, thaw it when an aliquot is requested, subdivide the remainder of the parent sample in small volumes to make additional aliquots for future tests and then refreeze these smaller volume aliquots to cryopreserve each aliquot separately until needed for a future test. This approach limits the number of freeze/thaw cycles to which a sample is exposed, but there is added expense associated with the larger volume of frozen storage space, labor, and larger inventory of sample containers (e.g. tubes, vials, or the like) required to maintain the cryopreserved aliquots. Moreover, the aliquots can be degraded or damaged by even a limited number freeze/thaw cycles.
Yet another approach is to divide a large volume sample into smaller volume aliquots before freezing them for the first time. This approach can limit the number of freeze thaw cycles to which a sample may be subjected to only one; yet, there are disadvantages associated with the costs of labor, frozen storage space, and sample container inventory requirements with this approach.
U.S. pre-grant publication No. 20090019877, the contents of which are hereby incorporated by reference, discloses a system for extracting frozen sample cores from a frozen biological sample without thawing the original (parent) sample. The system uses a drill including a hollow coring bit to take a frozen core sample from the original parent sample without thawing the parent sample. The frozen sample core obtained by the drill is used as the aliquot for the test. After the frozen core is removed, the remainder of the sample is returned to frozen storage in its original container until another aliquot from the parent sample is needed for a future test.
The present inventors have developed systems and methods, which will be described below, that improve the ability to provide frozen aliquots from a frozen sample using a system that extracts frozen sample cores from frozen samples without thawing the samples.